1. Field of the Invention
The present invention relates to an imaging apparatus for detecting an image in response to receiving radioactive rays such as X-rays, visible rays or infrared rays, more particularly to temperature control thereinside.
2. Description of the Background Art
FIG. 6 shows a conventional imaging apparatus.
A semiconductor layer 102 for converting an incident radioactive ray into charge information is vapor-deposited on an active matrix substrate 103 for reading the charge information. A bias electrode 119 is formed on the semiconductor layer 102. The active matrix substrate 103 is disposed on a front surface of a base substrate 105 through a buffer layer 118.
The charge information created through the semiconductor layer 102 is read by the active matrix substrate 103, and the read charge information is converted into a voltage by an amplifier circuit 104 mounted on a tape automated bonding (TAB) film 108 connected to the active matrix substrate 103. The converted voltage is converted into a digital signal by an image-signal processing circuit board 115.
Further, a power supply circuit board 111 is disposed on a rear surface of the base substrate 105 to supply various DC voltages produced through a DC-DC converter 112, to the active matrix substrate 103 and peripheral circuits thereof.
During operation, considerable heat is generated in the amplifier circuit 104, and the DC-DC converter 112 mounted to the power supply circuit board 111. Therefore, a heat pipe 151 is connected to a surface of each of the amplifier circuit 104 and the DC-DC converter 112 of the power supply circuit board 111 to discharge the generated heat so as to keep each of the amplifier circuit 104 and the DC-DC converter 112 at an approximately constant temperature (see, for example, JP 11-345956A).
However, the above conventional structure causes an increase in lateral width of the imaging apparatus, which constitutes a limiting factor of downsizing.
Further, in order to thermally stabilize the amplifier circuit 104, and a semiconductor device of the power supply circuit board 111, it is necessary to lay out the plurality of heat pipe 151 at respective positions, which leads to an increase in the number of components.
Moreover, the amplifier circuit 104 is located in adjacent relation to the semiconductor layer 102, which is likely to cause a temperature rise in the semiconductor layer 102. It is known that a material consisting mainly of amorphous selenium recrystallizes at 40° C. or more. Thus, if the amorphous selenium-based material is employed in the semiconductor layer 102, the temperature rise will pose a problem.